Discovery made by bed rest study crucial to health of future astronauts

It might seem like the easiest of studies, but being confined to a bed for 21 days as part of a bed rest study is no easy task, but it helps researchers better understand the effects of inactivity in the human body, particularly for astronauts.

Despite constantly moving to perform myriad different tasks aboard the International Space Station, significant parts of an astronaut’s body are left idle in zero gravity which could result in their muscles wasting away if they don’t perform daily exercise.

Dublin City University (DCU) and the 3U Diabetes Consortium have published a bed rest study in the journal Diabetologia that reveals some surprising results for both space travel and those of us on Earth.

Balanced diet isn’t enough

As part of the 3U Diabetes Consortium, the study collaborated with the European Space Agency’s PRODEX programme and Enterprise Ireland to get access to the bed rest study facilities.

Over the course of the three weeks, the researchers found, for the first time, that the body’s ability to regulate metabolism is tightly linked to the number of mitochondria – the powerhouse of our cells.

So, even though the participants were in energy balance and therefore did not gain fat mass, they lost muscle and became more resistant to insulin – which, for diabetic people on Earth, would be dangerous.

But with a type of simple exercise referred to as resistive vibration exercise, the harm caused to the body can be reduced and this came as a surprise to the lead researcher on the study, Dr Donal O’Gorman.

Surprising findings

“We were surprised that just five exercise sessions was sufficient to offset the changes in insulin sensitivity though we did not expect changes in all parameters,” he said.

“We believe that the mitochondria are quite resilient to the changes due to bed rest and that what we observe is partly a protective effect to try and preserve normal function.”

He continued: “We think this sets the foundation for health-related changes that happen later in life as the muscle can only compensate for a reasonable period of time before negative effects start to accumulate.”

Another interesting finding, O’Gorman added, was that even though energy balance was maintained (with energy intake matching energy expenditure throughout bed rest) there were still decreases in insulin sensitivity and muscle mass.

This indicates that even if we perfected the amount of energy consumed to stay healthy from a dietary perspective, some degree of physical activity will be needed to actually stay healthy overall.

The team’s findings can now aid astronauts in preparation for space travel and inform useful countermeasures while in space.

The next step for O’Gorman and his team is to follow up with another bed rest study, but this time over 60 days to determine if this nutritional intervention can offset some of the negative changes that occur during bed rest and space flight.